Hi,
I dont think i could tolerate their behaviour, you are the contractor and whilst its fine to negotiate on times, work, hours etc they have no right to tell you what to do, hoe to do it or even mention warnings.
I would definately call a meeting and explain what their responsibilities are and what yours are, explain what you are able to manage to do realistically with the time they have given you and stick to your guns, dont back down.
If you get nowhere then you never will and it could just get worse over time.
Give them notice if you have to and tell them to stick it, even if they get another contractor then fine let them have the problem and save yourself some stress.
Sarah x